1. Field of the Invention
The invention relates to a width-adjustable sheet tray, and more particularly to a width-adjustable sheet tray with a minimized sheet holding width using a belt to adjust the width.
2. Description of the Related Art
Automatic document feeders are widely used in scanners, printers and multi-function peripherals. The sheets to be placed in the automatic document feeder are typically determined by a user. So, the automatic document feeder is usually equipped with a left guiding component and a right guiding component for holding and guiding the sheets such that the user can manually make an adjustment according to the width of the sheet and the skew of the sheet being fed may be avoided.
The sheet width adjusting mechanism of a conventional automatic document feeder is usually composed of a gear and two racks, which are located at two sides of the gear and engage with the gear. When the user moves the left guiding component, the gear is rotated to move the right guiding component. Thus, the left guiding component and the right guiding component may be moved close to or away from each other synchronously.
The minimum width of the sheet that can be held and guided by the sheet width adjusting mechanism is restricted by the structures of the gear, the left guiding component and the right guiding component. Thus, the sheet, such as a long invoice having the width smaller than the minimum width, cannot be held and guided by the left guiding component and the right guiding component.
In addition, because the rack needs an elastic rib to press against the sliding slot, the rack does not pertain to the standard element, and the manufacturer has to additionally order the racks satisfying the requirement, and the manufacturing cost cannot be reduced.